Worth checking at local dealer as Dave Silver is Bout £95 inc.
Yes Roo i agree, unfortunately every one i have ever took apart with play has the collar worn more than the bushes.
The later 390 number part used on the F model that has the single grease nipple on the swing arm is discontinued, guess what------ you can use the early 300 one
Yes Bryan it always seem odd that the softer materials wears the harder one away.
Years ago car clutch pivots made of Nylon would wear the metal socket they fitted into having previously been made of metal.
It's an often missed but very simple process that wears the hard component with the soft Ted. Something that was part of my apprenticeship that's specifically designed to drum it into us the impact of various elements in engineering, we had to make a "puck" in high carbon steel, then impregnate with more carbon to increase the ultimate hardness of the material such that it moved it right to the extreme of testing on hardness evaluation equipment. Then to hand finishing the surface with nothing more than successive work on first cast iron plates, aluminium plates and finally brass plates, all having their surface embeded with cutting media (carborundum first, finished with diamond grit) to refine by cutting that hard steel.
This is exactly the same as something like emery cloth in concept (carborundum glued to denim material) in that it embeds highly abrasive particles into a soft base substrate. Also anything like sand paper etc and cutting disc on disc cutter.
The swing arm essentially has any wear particle from the sleeve embedded into the plastic, along with anything else that gets in there and gently works away cutting the steel away during use.
There's also another parallel in vehicles, especially those run without air filtration. The intake ingesting silicon oxide (silicon sand readily available from road surfaces etc) that mixes with the oils, lodges in components like piston, main bearings, aluminium head bearings etc to very effectively cut the main components and wear them out prematurely.